putObject: Streaming uploads with size -1 should avoid fetching previ…

…ous partsInfo.

size == -1 should be treated specially for putObjectStream() and avoid fetching
partsInfo for previously uploaded parts since '-1' has no guarantee that the
data has no changed. Let the client upload again and not resume for unknown sizes.

Fixes - minio/mc#1819

api-put-object-multipart.go

@@ -94,8 +94,9 @@ func (c Client) putObjectMultipartStream(bucketName, objectName string, reader i
 	}
 
 	// If This session is a continuation of a previous session fetch all
-	// previously uploaded parts info.
-	if !isNew {
+	// previously uploaded parts info and as a special case only fetch partsInfo
+	// for only known upload size.
+	if !isNew && size > -1 {
 		// Fetch previously uploaded parts and maximum part size.
 		partsInfo, err = c.listObjectParts(bucketName, objectName, uploadID)
 		if err != nil {
@@ -190,7 +191,12 @@ func (c Client) putObjectMultipartStream(bucketName, objectName string, reader i
 	for i := 1; i <= totalPartsCount; i++ {
 		part, ok := partsInfo[i]
 		if !ok {
-			return 0, ErrInvalidArgument(fmt.Sprintf("Missing part number %d", i))
+			// Error our only if we know exactly the right amount of part sizes.
+			if size > -1 {
+				return 0, ErrInvalidArgument(fmt.Sprintf("Missing part number %d", i))
+			}
+			// Breakout an finish the upload if size is -1.
+			break
 		}
 		complMultipartUpload.Parts = append(complMultipartUpload.Parts, completePart{
 			ETag:       part.ETag,